---
cve: "CVE-2026-45118"
severity: "CRITICAL"
cvss: 9.3
epss: "38%"
vendor: "MyBB"
kev: false
exploited: false
published: "2026-08-18 16:17:06"
tags: [cve, security, critical]
source: tsecurity.de CVE-Dossier
exported: "2026-09-08T08:54:33+02:00"
---

# CVE-2026-45118

> 9.3 CRITICAL · 🧪 PoC

## Beschreibung

MyBB is free and open source forum software. Prior to 1.8.40, the Contact module does not validate a redirect URL or protocol correctly, resulting in an open redirect and reflected JavaScript code injection. contact.php accepts the redirect target from the from HTTP parameter in $mybb->input['from'] or the Referer HTTP header in $_SERVER['HTTP_REFERER'] and passes it to redirect() without sufficient verification. A javascript: URI becomes the target of the `Click here if you don't want to wait any longer` link because $force_redirect is true, allowing script execution when a victim selects the link. This issue is fixed in version 1.8.40.

## CVSS-Vektor

```
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N
```

| Metrik | Wert | Bewertung |
|---|---|---|
| AV Angriffsvektor | Netzwerk | bad |
| AC Komplexität | Gering | bad |
| PR Privilegien | Keine | bad |
| UI Interaktion | Erforderlich | good |
| S Scope | Verändert | bad |
| C Vertraulichkeit | Hoch | bad |
| I Integrität | Hoch | bad |
| A Verfügbarkeit | Keine | good |

## Patch verfügbar (OSV)

- e9942c6d19ac1709b3df7357cfb8810774c8d3ac (Commit)

## Referenzen

- <https://github.com/mybb/mybb/security/advisories/GHSA-wf92-5q5h-qr53>
- <https://github.com/mybb/mybb/releases/tag/mybb_1840>
- <https://mybb.com/versions/1.8.40>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2026-45118) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_